A flask contains a mixture of isohexane and 3 -methylpentane. One of the liquids boils at \(63^{\circ} \mathrm{C}\) while the other boils at \(60^{\circ} \mathrm{C}\). What is the best way to separate the two liquids and which one will be distilled out first?

(D) fractional distillation, isohexane

(A) fractional distillation, 3-methylpentane

(B) simple distillation, isohexane

(C) simple distillation, 3-methylpentane

JEE Main · 2020 · 08 Jan 2020 · Shift 1 · Practical and Analytical Chemistry

A flask contains a mixture of isohexane and 3 -methylpentane. One of the liquids boils at

6 3^{\circ} C

while the other boils at

6 0^{\circ} C

. What is the best way to separate the two liquids and which one will be distilled out first?

(A)fractional distillation, 3-methylpentane
(B)simple distillation, isohexane
(C)simple distillation, 3-methylpentane
(D)fractional distillation, isohexane✓ Correct

Answer: (D)

Solution

Isohexane and 3-methylpentane are isomers boiling at

6 0^{\circ}

C and

6 3^{\circ}

C, only

3^{\circ}

apart, and such close boiling points call for fractional rather than simple distillation. In fractional distillation the lower-boiling component comes over first, so isohexane, boiling at

6 0^{\circ}

C, distils out ahead of 3-methylpentane.

JEE Main · 2020 · 08 Jan 2020 · Shift 1 · Single correct option

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JEE Main · 2020 · 08 Jan 2020 · Shift 1 · Practical and Analytical Chemistry

Solution

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